1. Field of the Invention
The present invention relates to a cutting machine for synthetic resin pipes, and more particularly to a handy cutting type of machine.
2. Description of the Prior Art
As a cutting machine of this kind, the present inventor has previously developed a cutting machine comprising a machine body for holding a synthetic resin pipe subjected to cut work, a plate-like cutter provided on the machine body for advancing and retracting movement with respect to the pipe within a plane perpendicularly intersecting the center line of the pipe, and a drive means for the cutter provided on the machine body, the cutter being provided at an edge opposite to the pipe with an angled cutting blade having a width in a direction perpendicular to the advancing and retracting direction of the cutter larger than the outer diameter of the pipe, the angled cutting blade being composed of a bight portion passing through the center of the pipe and being positioned on an imaginary straight line parallel with the advancing and retracting direction of the cutter, and first and second inclined portions continuous to the bight portion and symmetrical with respect to said imaginary straight line.
It has been found however that the aforementioned cutting machine still need be improved as follows:
That is, when the cutting work starts, the bight portion of the cutting blade presses the peripheral wall of the pipe toward of the center thereof, and therefore, in the case where the pipe has a large diameter and a thin wall thickness, deformation, breakage or the like of the pipe may occur.
In addition, after the cutting work has been started, the peripheral wall of the pipe is cut by the first and second inclined portions. However, when the bight portion bites or stings the inner peripheral surface of the pipe in an intermediate process of the operation, the cutting by the bight portion and the cutting by both the inclined portions are simultaneously carried out, and cut portions in the pipe increase to three which had been previously two and therefore, a great force is required to move the cutter forward, and the rigidity of the cutting machine need be enhanced accordingly.